Process of making motor spirits and refining petroleum products



Patented Nov. 24, 1925.

UNITED STATES PATENT OFFICE.

BENJAMIN T. BROOKS, 0F BAYSIDE, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 CARBIDE AND CARBON CHEMICALS CORPORATION, A CORPORATION OF NEW YORK.

PROCESS OF MAKING MOTOR SPIRITS AND REFINING PETROLEUM PRODUCTS.

This invention relates to a process of making motor spirit, and of refining petroleum products.

In carrying out this process, the starting material is a petroleum product, as, for example, either crude petroleum, or the distillates or residues obtained from crude petroleum. In practice, the petroleum product known as gas oil, is particularly applicable, because it consists chiefly of high boiling hydrocarbons of the aliphatic series, which are especially suitable for carrying out the present process and, furthermore, it is a cheap starting material at the present time. The starting material .is. cracked under such conditions as to give a resultant liquid product rich in hydrocarbons of the olefin series.

In the cracking processes hitherto employed for the production of motor spirit, it has been, customary either to crack the oil at relatively low temperatures; for example, below 600 C., or to erform the cracking operation under relatively high pressures; that is to say, at pressure of two atmospheres or above. The purpose of maintaining the low temperatures, when cracking at atmospheric pressures or thereabouts or of employing the high pressures, has been to avoid as much as possible the production of unsaturated hydrocarbons such as olefins in the product. The production of some olefins has been considered unavoidable but generally efiforts were made to reduce the proportion of such bodies to a minimum.

While some attempts have heretofore been made to utilize as motor spirit certain low boilin petroleum sidera le olefins, t ese attempts have not been satisfactory.

The present applicant has found that the difliculties have eenjdue to the fact that in the production of such motor spirit not only olefins, but also diolefins and certain malodorous substances, such as pyridine bases,

roducts containing con 1918. Serial no. 231,802.

sulphur compounds and naphthenic acids, exist in the final product.

By the present invention a petroleum product is used as a starting material and is subjected to a cracking process under conditions such as to give a good percentage of low boiling olefins, liquid at normal temperatures. The conditions of which will give this result are well known, but have generally been avoided heretofore in the manufacture of motor spirit. Under such cracking process, the low boiling constituents comprise saturated hydrocarbons and also olefins. Sometimes there may be aromatic hydrocarbons present, but these need not be specially considered at the present time as they are an advantage in the final product and are not affected by the refining process comprising an essential'feature of the present invention.

The olefins in the cracked product will comprise some diolefins. These are not only present invention, it is important to crack cracking the petroleum product under conditions which will give an olefin-rich cracked product and then distil the same in the usual way to obtain the low boiling fractions.

At the same time,'it is to be understood thatthe invention not limited to any particular cracked product, since the refining steps hereinafter described are applicable to any petroleum product.

In carrying out the present process, the product of the cracking process is mixed with 5 per cent by volume of an aqueous solution of sulfuric acid of Baum gravity materially less than 60, containin for example about 7 5 to 80 per cent H 0,, and then thoroughly agitated for about half an hour, at ordinary temperature. .The mixture is then allowed to stand until it stratifies. It will be found that layers of acid and is to say, there is no fractionating.

The distillate is a clear product forming an excellent motor spirit having no unpleasant odor and not deteriorating either by decomposition or otherwise when kept or a considerable time.

When used as motor spirit it volatilizes satisfactorily in the usual carbureters such as are employed for the so-called commercial gasolines now in general use and the power output by volume is excellent.

This product contains parafiinsand olefins, but seems to be substantially free from diolefins or derivatives thereof, and from hydrocarbons of the acetylene series. A

Instead of carrying out the process as described above, it may be modified while still attaining the desired result. For example, instead of treating the product of a petroleum cracking process with sulfuric acid in an unconcentrated condition, it may be treated with ground niter cake or sodium acid sulfate or other acid sulfate, or a mixture of such acid sulfates. The other steps of the process may be the same as before.

Furthermore, instead of washing the product with an alkali wash, it may be treated with soda-lime. Great advantage in the purifying of such products results from the use of soda-lime, due in part to. the physical properties of the soda-lime.

In subjecting the petroleum product to the treatment with soda-lime, several methods may be employed. For example, the soda-lime and hydrocarbon material may be mixed and agitated, then allowed to settle and the purified product drawn off. Or the hydrocarbon material may be percolated through a layer of soda-lime. Further, the soda-lime may be used in the still when redistilling the product. In carrying out this treatment, the soda-lime may be placed either in the body-of the oil in the still, or it may be placed as a body or layer in the path of the vapors evolved by the still, so that said vapors must traverse the body or layer of soda-lime.

The soda-lime, owing to its porosity and capability of retaining its shape, forms an admirable material for the passage of the hydrocarbon liquid or vapor through its mass.

' By using a relatively dilute or non-concentrated sulfuric acid as specified above, in refining a product containing acetylenes or diolefins, very important results are attained as compared with the use of concentrated sulfuric acid. For example, when concentrated acid is used the loss of product to the acid is large, much tar is dissolved in the acid making the acid recovery difiicult, sulpho-acids are formed in relatively large amounts and the mono-olefins are attacked, being in part dissolved and in part polymerized to form oils and tars.

On re-distilling such a product treated with concentrated sulfuric acid, a yellow distillate is obtained and much S0 is given off Also the high boiling residue is large. By the present process, when the sulfuric acid is dilute, the loss to acid is small, tars are only partly dissolved by the acid, the sulpho-acids are formed only to a slight extent, mono-olefins are practically unaffected, and on re-distillation of this product there is little S0 and the distillate is white. Diolefins are resinified and thus removed while all malodorous nitrogen bases are removed. The subsequent recovery or regeneration of the sulphuric acid is more efficient since it contains less dissolved organic matter, in the presence of which the sulphuric acid is de composed to S0 and water, and certain oxidized products of the organic matter are formed.

lVhat is claimed is:

'1. The process of making motor spirit which comprises cracking a petroleum product under conditions giving a material rich in olefins, subjecting this material to the action of a sulphuric acid equivalent to strong aqueous H 530 of Baum gravity materially less than 66, separating the oil from the substances immiscible therewith, treating the separated oil with an alkali, and distilling off and collecting the oil.

2. The process of treating distillates produced by the cracking of petroleum oils which comprises subjecting said distillates to the action of a sulphuric acid equivalent to strong aqueous H SO, of a Baum gravity materially less than 66, separating said distillates from the substances immiscible therewith, treating the said separated distillates with an alkali and distilling oil and collecting said distillates.

In testimony whereof, I have hereunto set my hand.

BENJAMIN T. BROOKS. 

